Hip joint

The hip joint (art. coxae) is formed by the crescent surface of the acetabulum of the pelvic bone and the head of the femur. The articular surface of the pelvic bone is enlarged by the acetabular labrum (labrum acetabulae). It is a fibrocartilaginous formation firmly fused with the edges of the acetabulum. The transverse acetabular ligament (lig. transversum acetabuli) is thrown over the notch of the acetabulum. The joint capsule of the hip joint is attached along the circumference of the acetabulum, so the acetabular labrum is located in the joint cavity. On the femur, the capsule is attached along the intertrochanteric line, and behind - on the neck of the femur near the intertrochanteric crest, so the entire neck is in the joint cavity. The joint capsule is strong, reinforced with powerful ligaments. In the thickness of the fibrous membrane of the hip joint there is a thick ligament - the circular zone (zona orbicularis), embracing the neck of the femur in the form of a loop. This ligament is attached to the ilium under the inferior anterior iliac spine. The iliofemoral ligament (lig. iliofemoral), Bertinius's ligament, begins on the inferior anterior iliac spine and is attached to the intertrochanteric line, has a thickness of about 1 cm. This is the strongest ligament, withstanding a load of up to 300 kg. The pubofemoral ligament (lig. pubofemoral) goes from the superior branch of the pubic bone and the body of the ilium to the medial part of the intertrochanteric line. The ischiofemoral ligament (lig. ischiofemorale) is located on the posterior surface of the joint. It begins on the body of the ischium, goes outward and almost horizontally, ends at the trochanteric fossa of the greater trochanter. In the joint cavity there is a ligament of the head of the femur (lig. capitis femoris) covered with a synovial membrane, connecting the head of the femur and the edges of the acetabulum notch. This ligament plays a role during the formation of the hip joint in the fetus and after birth, holding the head of the femur to the acetabulum.

The hip joint is a cup-shaped joint (art. cotylica) in terms of the shape of its articular surfaces - a type of ball-and-socket joint. Flexion and extension are possible around the frontal axis. The range of this movement depends on the position of the shin in the knee joint. Maximum flexion (about 120°) is achieved with a flexed shin. With an extended shin, the range of flexion (up to 85°) is reduced due to the tension of the posterior group of thigh muscles. Extension in the hip joint is achieved with a small range (up to 13-15°) due to the braking effect of the iliofemoral ligament. Abduction and adduction of the limb relative to the midline (up to 80-90°) are achieved around the sagittal axis in the hip joint. The total range of rotational movements (around the vertical axis) reaches 40-50°. Circular movement is possible in the joint.

In general, the range of motion performed in the hip joint is much less than in the shoulder. The hip joint, however, is stronger, reinforced by powerful ligaments and strong muscles.

On the radiograph of the hip joint, the head of the femur is rounded, and the fossa of the head is visible as a depression on its medial surface. The greater trochanter is located on the line between the anterior superior iliac spine and the ischial tuberosity. The contours of the X-ray joint space are clear.

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